Electrochemical additive manufacturing of cicada-inspired fluoridated hydroxyapatite nanostructured surfaces

We use electrochemical additive manufacturing method to combine cicada-inspired nanostructures and fluoridated hydroxyapatite (FHA) solutions, and give full play to their physical and chemical antibacterial advantages. We prepared cicada-inspired fluoridated hydroxyapatite nanostructured surfaces on the surface of acid etched titanium for the first time. It consists of closely aligned single FHA nanopillars. The diameter of a single FHA nanopillar is about 65-95 nm, the height is about 380-510 nm, and the aspect ratio is about 4.5-7. It has high crystallinity, long-range regularity and defect free lattice with the [0001] (i.e. [001], c-axis) crystallographic orientation. It is expected to be applied to orthopedic and dental implant surgery in the future.

Introduction: With the rapid development of modern medicine, implant surgery has gradually become more important. However, due to the use of antibiotics, the bacterial infection of implantation becomes difficult to overcome. Therefore, we urgently need to find non-antibiotic antibacterial methods. Recently, cicada-inspired nanostructures and fluoridated hydroxyapatite (FHA) solutions have attracted great interest for their remarkable bactericidal ability. But cicada-inspired nanostructures are not resistant to Gram-positive bacteria. In this study, we aimed to develop fabricating nano-structures with bioactive and biocompatible properties.

Results & Discussion: The cicada-inspired FHA nanostructure deposition layer was successfully formed on an AETi plate of which size is 9 × 9 × 1 mm. It consists of closely aligned single FHA nanopillars. The diameter of a single FHA nanopillar is about 65-95 nm, the height is about 380-510 nm, and the aspect ratio is about 4.5-7. The fluorine concentration (2.22 at.%) and Ca/P ratio (1.61) are similar to those of the Ca₁₀(PO₄)₆(OH)F (fluorine concentration = 2.33 at.%, Ca/P = 1.67).

Conclusions: This study provide a novel, economical and time-saving method to prepare cicada-inspired nanostructured surfaces, which may enhance the antibacterial activity of orthopedic and dental implants and lay the foundation for better biological applications in the future.